1. Field of the Invention
This invention relates to an electrical supply unit, and in particular concerns an electrical supply unit which may safely be used to charge battery powered tools in a construction or other work site environment.
2. Description of the Related Art
In many jurisdictions, for instance the United Kingdom, it is forbidden or strongly discouraged to provide power outlets at “mains” voltage on or near a building or site or other work site. Instead, power supply points supplying a significantly lower “site voltage” are generally available on site. As an example, mains voltage in the United Kingdom is 240V, but site voltage is only 110V.
The majority of powered tools used on building sites are portable and battery-powered, and the batteries of these tools need to be recharged. The charging of batteries for such tools at site voltage is generally very slow if at all possible, and it is much preferred to charge such batteries at mains voltage. Unfortunately, in the environment of a typical building site, no mains power points are available and the only such points may be located in a central contractor's office. In such sites, any mains power points are generally used almost permanently for the charging of batteries for power tools, and this is one reason why such offices are often designated as “out of bounds” to the workforce.